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SU11.1-6 | Anaesthesia and Pain Management — Practice Quiz
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A 70 kg adult is to receive plain lignocaine (lidocaine) for infiltration of a wound, with no adrenaline added. What is the maximum recommended dose, and therefore the largest volume of 1% plain lignocaine that may safely be infiltrated?
Correct. Plain lignocaine has a maximum dose of 3 mg/kg. For a 70 kg adult that is 210 mg. A 1% solution is 10 mg/mL, so 210 mg = 21 mL. Adrenaline-containing lignocaine raises the ceiling to 7 mg/kg by slowing systemic absorption.
Lignocaine max dose: 3 mg/kg plain, 7 mg/kg with adrenaline. A 1% solution = 10 mg/mL. Always convert mg/kg to a volume before infiltrating.
The 7 mg/kg figure applies only when adrenaline is added. Plain lignocaine is limited to 3 mg/kg (210 mg in a 70 kg adult). With a 1% solution at 10 mg/mL, 210 mg equals 21 mL.
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Five minutes after a surgeon injects a large volume of bupivacaine for a regional block, the patient becomes agitated, complains of perioral tingling and a metallic taste, then has a generalised seizure followed by a broad-complex cardiac arrest. Which feature of bupivacaine most explains the refractory cardiac arrest, and what is the specific antidote?
Correct. This is local anaesthetic systemic toxicity (LAST). Bupivacaine binds avidly to cardiac sodium channels, making its cardiac toxicity disproportionately severe and resistant to standard resuscitation. The specific treatment is intravenous 20% lipid emulsion, which acts as a 'lipid sink', alongside standard ACLS.
LAST presents with CNS signs first (perioral numbness, metallic taste, seizures) then cardiovascular collapse. Bupivacaine is the most cardiotoxic agent; treat with IV 20% lipid emulsion plus standard resuscitation.
The picture — CNS excitation (perioral tingling, metallic taste, seizure) progressing to cardiac arrest after a local anaesthetic — is local anaesthetic systemic toxicity. Bupivacaine is especially cardiotoxic, and the specific antidote is intravenous 20% lipid emulsion (intralipid).
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The classical triad of general anaesthesia describes the three goals an anaesthetist must achieve. Which option lists the three components of this triad?
Correct. The triad of general anaesthesia is hypnosis (unconsciousness), analgesia (suppression of pain), and muscle relaxation (akinesia). Modern balanced anaesthesia uses separate drugs to achieve each component.
Triad of GA = hypnosis + analgesia + muscle relaxation. Balanced anaesthesia targets each component separately, reducing the dose and side effects of any single agent.
The triad of general anaesthesia is hypnosis (unconsciousness), analgesia, and muscle relaxation. Balanced anaesthesia uses a separate agent for each goal rather than a single deep dose of one drug.
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A young man needs an emergency lower-limb procedure and is given a single subarachnoid (spinal) injection. Compared with epidural anaesthesia, which statement about this spinal technique is correct?
Correct. A spinal (subarachnoid) block delivers a small dose of local anaesthetic directly into the CSF, producing a rapid-onset, dense, well-demarcated block. Epidural anaesthesia uses a larger dose in the epidural space, has slower segmental onset, and is usually catheter-based for prolonged dosing.
Spinal: small dose into CSF, fast dense block, single shot. Epidural: larger dose into epidural space, slower segmental block, catheter for top-ups. Both cause sympathetic blockade and hypotension.
Spinal anaesthesia injects a small dose into the CSF for a rapid, dense block; the catheter-based, larger-dose, slow-onset technique is the epidural. Both block sympathetic fibres and can cause hypotension.
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An unconscious supine patient is making see-saw chest and abdominal movements with no breath sounds and a falling oxygen saturation. The commonest cause of upper airway obstruction in this situation is the tongue falling back. Which simple manoeuvre is the first-line, non-invasive way to relieve it?
Correct. Silent obstruction with paradoxical see-saw movement in the unconscious supine patient is usually the tongue falling back. The first step is a head-tilt chin-lift (or a jaw thrust if the cervical spine must be protected), which lifts the tongue off the posterior pharyngeal wall.
Airway ladder: start simple — head-tilt chin-lift / jaw thrust to relieve the tongue, then airway adjuncts, then a definitive airway. Complete obstruction is SILENT with paradoxical see-saw movement.
The first-line manoeuvre for tongue-base obstruction is a head-tilt chin-lift, or a jaw thrust when cervical injury is a concern. Surgical airways and intubation come later in the escalation ladder, not first.
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An anaesthetist is choosing an airway device. She wants a device that sits in the hypopharynx over the laryngeal inlet, is quick to insert, but does NOT provide a sealed, definitive airway protecting against aspiration. Which device is she describing?
Correct. The LMA is a supraglottic device that sits over the laryngeal inlet and is quick to place, but it does not seal the trachea and so does not fully protect against aspiration. A cuffed ETT is the definitive airway that does protect the airway.
LMA = supraglottic, fast, but does NOT protect against aspiration. The cuffed ETT is the definitive, aspiration-protecting airway. Choose based on aspiration risk and surgical need.
A device placed over the larynx that is quick to insert but does not protect against aspiration is the supraglottic LMA. A cuffed endotracheal tube, tracheostomy, or cricothyroidotomy all provide a sealed, definitive airway.
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A surgeon is selecting patients for a daycare (ambulatory) surgery list. Which patient is the MOST appropriate candidate for same-day discharge?
Correct. Daycare surgery depends on selection: a fit ASA I/II patient, a short low-complication procedure such as hernia repair, and adequate social support (a responsible escort and home help) are the core criteria. The other patients fail on patient fitness, procedure complexity, or social/geographic grounds.
Daycare selection rests on three groups of factors: patient fitness (ASA I/II), procedure (short, low-complication, low bleeding/pain), and social/geographic support (responsible escort, reachable, able to care at home).
The ideal daycare candidate is a fit ASA I/II patient having a short, low-complication operation with good social support. High ASA grade, major or prolonged surgery, heavy opioid needs, or inadequate home support are all contraindications.
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The WHO analgesic ladder guides post-operative pain relief. According to its principles, how should post-operative pain ideally be managed?
Correct. Post-operative pain should be anticipated and prevented, not merely treated once severe. Multimodal analgesia (combining paracetamol, NSAIDs and opioids with regional techniques) is given regularly and stepped up the WHO ladder according to severity, reducing opioid dose and side effects.
Post-op analgesia: anticipate and prevent, give regularly, use multimodal drugs, and step up the WHO ladder by severity. Unexpectedly severe or escalating pain signals a complication (bleeding, ischaemia, infection).
Good post-operative analgesia is anticipatory, regular and multimodal, stepping up the WHO ladder by severity — not reactive single-agent opioid use once pain is severe. Note that unexpectedly escalating pain is itself a warning sign of a complication.
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